Design and numerical analysis of high birefringence and high nonlinearity octagonal chalcogenide photonic crystal fiber in optical communication band

Photonic crystal fiber (PCF) with its flexibility in structural design and excellent optical control characteristics, it shows significant application value in the precise optical system that requires strict polarization characteristics and the scene that needs to strengthen the interaction between strong light and medium. In this study, we propose a novel octagonal PCF structure featuring asymmetric elliptical air holes in the core region, arranged in a rhombic configuration. By employing the full-vector finite-element method (FV-FEM) implemented within multiphysics simulation software, we numerically investigate the optical properties of an octagonal chalcogenide photonic crystal fiber, including birefringence, confinement loss, and the nonlinear coefficient. Numerical results indicate that, with optimized air hole distribution, a high birefringence value of 0.2916 can be achieved at the wavelength of 1.55 µm. Additionally, the confinement losses for x- and y-polarized modes are reduced to \(\:1.39\times\:{10}^{-5}\)dB/m and \(\:1.88\times\:{10}^{-9}\)dB/m, respectively, while the nonlinear coefficients reach \(\:3.59\times\:{10}^{5}{W}^{-1}\cdot\:{km}^{-1}\)and \(\:3.07\times\:{10}^{5}{W}^{-1}\cdot\:{km}^{-1}\). These characteristics provide new ideas for the related polarization control technology and the optimization design of nonlinear optics devices. ·